Permanent wave hair curlers have long been known, of the type in which a cylindrical rod or member is used to roll the hair while it is wet from the permanent waving solution. A strip or band of flexible material is attached at one end to an end of the rod, and the other end of the strip or band is arranged to be attached to the other end of the rod, whereby the hair wound upon the rod is held in place. For example, see Jacobs, U.S. Pat. No. 2,244,707.
The known permanent wave curlers are somewhat inconvenient for the operator in use, since the bands must be relatively accurately aligned with the holding arrangement on the rods, and/or the band must be stretched to perform the attachment. All of this must be accomplished while the rod and strap, the hair, and the operator's fingers are wet and slippery from the permanent waving solution.
Gilman, U.S. Pat. No. 3,923,068, addresses this problem with his magnetic attachment method. Such a rod cannot hold with the required strength, however, as the magnetic attraction has no resistance to the radial or sliding force (perpendicular to the rod axis) generated by the pull on the strap, and insufficient resistance against a pull along the axis of the rod.
Another problem with the prior art rods such as Jacobs or Gilman is the adverse effect that the thin strap has upon the hair compressed underneath. The thin edge gives rise to a "crimp" in the hair, which in turn, promotes breakage. A broader strap would eliminate this problem, but accentuates the inconvenience of use related above, and can add substantially to the complexity and expense of the rod. For example, Thackeray, U.S. Pat. No. 3,433,233, shows a relatively broad strap, which is not adjustable as to position on the end of the rod. If the strap does not "catch" exactly, it will pop off.
A better method of rolling uses a broad strap which is slotted to permit the hair to pass through the strap. The hair is placed against the rod and rolled up toward the hair roots until the rod rests against the strap. The rod must then be secured tightly in place. Past designs of this sort have exhibited some or all of the problems indicated above. Peterson, U.S. Pat. No. 2,123,378, for example, has a ratchet arrangement which is complicated to manufacture, difficult to use, and requires accurate alignment. Polykranas, U.S. Pat. No. 2,754,831, suffers from the same failings. He eliminates the ratchet in favor of a hex fitting into a slot, which method is limited in adjustability, and prone to wearing of the hex. The small metal pieces into which the slot is cut can easily bend, or the strap can flex, resulting in the hex leaving the slot and the hair unrolling.